In a Judo competition, the aim is to use a combination of these techniques to either throw an opponent onto their back with full control, to immobilise them on their back, or to force them to submit through a strangle or armbar.
Below is a list of five main sets of techniques that are used for grading. It should also be remembered that there are also countless variations, combinations and counters!

Other Technique References:

The internet, in particular YouTube is full of videos that break down judo techniques and show how they are executed in competition. These are fantastic resources. For discrete techniques there are 2 Judo websites that contain animations as well as video of more traditional execution of technique: